Calculadora de Calor de Reação (Entalpia)

This calculator determines the enthalpy of a chemical reaction (ΔH_rxn) using two main methods. The first method is based on Hess's law, using standard enthalpies of formation (ΔHf) of reactants and products. The second method calculates the heat involved (Q) from mass, specific heat, and temperature change of the substance. The formula applied is ΔH = Σ ΔHf(products) − Σ ΔHf(reactants) for the thermodynamic method, and Q = m·c·ΔT for the calorimetric method.

You can use this tool in situations such as: predicting whether a reaction is exothermic or endothermic, calculating energy released or absorbed in industrial processes, sizing heating or cooling systems in laboratories, and verifying data from thermodynamic tables. It is useful for chemistry students, chemical engineers, and professionals working with reactions at pilot or industrial scale.

Important precautions: make sure to use formation enthalpies at standard state (298 K, 1 atm) and with correct phases (solid, liquid, gas). The stoichiometric coefficients from the balanced equation must be entered as multipliers. For the Q = m·c·ΔT method, the specific heat must be consistent with mass and temperature units. Remember that ΔH is a state function and depends on pressure and temperature; tabulated values are for standard conditions.

The calculator provides the result in kJ/mol or kJ, depending on the method. For reactions with multiple reactants or products, sum the contributions of each substance. Check that the reaction is balanced before using the formation enthalpy method. If in doubt, consult the FAQ below.